In this type of system, radio wave protection guidelines such as, for example, guidelines of international commission on non-ionizing radiation protection (ICNIRP) are complied with. For example, Patent literature 1 describes a system configured to determine whether or not there is a human in an indoor space, and supply electric power low enough not to influence a human body if it is determined that there is a human in the indoor space, while supplying high electric power if it is determined that there is no human in the indoor space.